/**
 * 
 */
package com.sunnada.edu.system.pub.util;

import java.io.ByteArrayInputStream;
import java.io.ByteArrayOutputStream;
import java.net.URLDecoder;
import java.security.Key;
import java.security.KeyFactory;
import java.security.KeyPair;
import java.security.KeyPairGenerator;
import java.security.PrivateKey;
import java.security.Provider;
import java.security.PublicKey;
import java.security.Signature;
import java.security.interfaces.RSAPrivateKey;
import java.security.interfaces.RSAPublicKey;
import java.security.spec.PKCS8EncodedKeySpec;
import java.security.spec.X509EncodedKeySpec;
import java.util.HashMap;
import java.util.Map;

import javax.crypto.Cipher;

import org.apache.commons.codec.binary.Hex;
import org.bouncycastle.jce.provider.BouncyCastleProvider;

/**
 * 功能：RSA公钥/私钥/签名工具包
 * 可以用RSA进行公钥/密钥签名
 * 可以用RSA进行非对称加密
 * 字符串格式的密钥在未在特殊说明情况下都为BASE64编码格式
 * 由于非对称加密速度极其缓慢，一般文件不使用它来加密而是使用对称加密
 * 由于非对称加密速度极其缓慢，一般文件不使用它来加密而是使用对称加密
 * 非对称加密算法可以用来对对称加密的密钥加密，这样保证密钥的安全也就保证了数据的安全
 * 
 */
public class RSA {
	
	/** *//**
     * 加密算法RSA
     */
    private static final String KEY_ALGORITHM = "RSA";
    
    /** *//**
     * 签名算法
     */
    private static final String SIGNATURE_ALGORITHM = "MD5withRSA";

    /** *//**
     * 获取公钥的key
     */
    private static final String PUBLIC_KEY = "RSAPublicKey";
    
    /** *//**
     * 获取私钥的key
     */
    private static final String PRIVATE_KEY = "RSAPrivateKey";
    
    /** *//**
     * RSA最大加密明文大小
     */
    private static final int MAX_ENCRYPT_BLOCK = 117;
    
    /** *//**
     * RSA最大解密密文大小
     */
    private static final int MAX_DECRYPT_BLOCK = 128;

    /** 默认的安全服务提供者 */
    private static final Provider DEFAULT_PROVIDER = new BouncyCastleProvider();
    
    /** *//**
     * <p>
     * 生成密钥对(公钥和私钥)
     * </p>
     * 
     * @return
     * @throws Exception
     */
    public static Map<String, Object> genKeyPair() {
    	Map<String, Object> keyMap = new HashMap<String, Object>(2);
        try{
        	KeyPairGenerator keyPairGen = KeyPairGenerator.getInstance(KEY_ALGORITHM);
            keyPairGen.initialize(1024);
            KeyPair keyPair = keyPairGen.generateKeyPair();
            RSAPublicKey publicKey = (RSAPublicKey) keyPair.getPublic();
            RSAPrivateKey privateKey = (RSAPrivateKey) keyPair.getPrivate();   
            keyMap.put(PUBLIC_KEY, publicKey);
            keyMap.put(PRIVATE_KEY, privateKey);
        }catch(Exception e){
        	e.printStackTrace();
        }
        return keyMap;
    }
    
    /** *//**
     * <p>
     * 用私钥对信息生成数字签名
     * </p>
     * 
     * @param data 已加密数据
     * @param privateKey 私钥(BASE64编码)
     * 
     * @return
     * @throws Exception
     */
  /*  public static String sign(byte[] data, String privateKey) throws Exception {
        byte[] keyBytes = ConvertUtil.convertDecodeBase64(privateKey);
        PKCS8EncodedKeySpec pkcs8KeySpec = new PKCS8EncodedKeySpec(keyBytes);
        KeyFactory keyFactory = KeyFactory.getInstance(KEY_ALGORITHM);
        PrivateKey privateK = keyFactory.generatePrivate(pkcs8KeySpec);
        Signature signature = Signature.getInstance(SIGNATURE_ALGORITHM);
        signature.initSign(privateK);
        signature.update(data);
        return ConvertUtil.convertEncodeBase64(signature.sign());
    }*/

    /** *//**
     * <p>
     * 校验数字签名
     * </p>
     * 
     * @param data 已加密数据
     * @param publicKey 公钥(BASE64编码)
     * @param sign 数字签名
     * 
     * @return
     * @throws Exception
     * 
     */
/*    public static boolean verify(byte[] data, String publicKey, String sign)
            throws Exception {
        byte[] keyBytes = ConvertUtil.convertDecodeBase64(publicKey);
        X509EncodedKeySpec keySpec = new X509EncodedKeySpec(keyBytes);
        KeyFactory keyFactory = KeyFactory.getInstance(KEY_ALGORITHM);
        PublicKey publicK = keyFactory.generatePublic(keySpec);
        Signature signature = Signature.getInstance(SIGNATURE_ALGORITHM);
        signature.initVerify(publicK);
        signature.update(data);
        return signature.verify(ConvertUtil.convertDecodeBase64(sign));
    }*/

    /** *//**
     * <P>
     * 私钥解密
     * </p>
     * 
     * @param encryptedData 已加密数据
     * @param privateKey 私钥(BASE64编码)
     * @return
     * @throws Exception
     */
  /*  public static byte[] decryptByPrivateKey(byte[] encryptedData, String privateKey)
            throws Exception {
        byte[] keyBytes = ConvertUtil.convertDecodeBase64(privateKey);
        PKCS8EncodedKeySpec pkcs8KeySpec = new PKCS8EncodedKeySpec(keyBytes);
        KeyFactory keyFactory = KeyFactory.getInstance(KEY_ALGORITHM);
        Key privateK = keyFactory.generatePrivate(pkcs8KeySpec);
        Cipher cipher = Cipher.getInstance(keyFactory.getAlgorithm());
        cipher.init(Cipher.DECRYPT_MODE, privateK);
        int inputLen = encryptedData.length;
        ByteArrayOutputStream out = new ByteArrayOutputStream();
        int offSet = 0;
        byte[] cache;
        int i = 0;
        // 对数据分段解密
        while (inputLen - offSet > 0) {
            if (inputLen - offSet > MAX_DECRYPT_BLOCK) {
                cache = cipher.doFinal(encryptedData, offSet, MAX_DECRYPT_BLOCK);
            } else {
                cache = cipher.doFinal(encryptedData, offSet, inputLen - offSet);
            }
            out.write(cache, 0, cache.length);
            i++;
            offSet = i * MAX_DECRYPT_BLOCK;
        }
        byte[] decryptedData = out.toByteArray();
        out.close();
        return decryptedData;
    }*/
    
	/**
	 * 使用指定的私钥解密数据。
	 * 
	 * @param privateKey
	 *            给定的私钥。
	 * @param data
	 *            要解密的数据。
	 * @return 原数据。
	 */
	private static byte[] decrypt(PrivateKey privateKey, byte[] data)
			throws Exception {
		 Cipher ci = Cipher.getInstance(KEY_ALGORITHM, DEFAULT_PROVIDER);
		ci.init(Cipher.DECRYPT_MODE, privateKey);
		return ci.doFinal(data);
	}

	// 分段解密
	public final static String decrypt(String data, PrivateKey rk) {
		String rrr = "";
		StringBuffer sb = new StringBuffer(100);
		StringBuffer sbtemp = new StringBuffer();
		try {
			ByteArrayInputStream bais = new ByteArrayInputStream(
					data.getBytes());
			// 此处之所以是 256，而不是128的原因是因为有一个16进行的转换，所以由128变为了256
			byte[] readByte = new byte[256];
			int n = 0;
			while ((n = bais.read(readByte)) > 0) {
				if (n >= MAX_DECRYPT_BLOCK) {
					sbtemp.setLength(0);
					sbtemp.append(new String(decrypt(rk, hex2byte(readByte))));
					sb.append(sbtemp.reverse());
				} else {
				}
			}
			rrr = URLDecoder.decode(sb.toString(), "UTF-8");
		} catch (Exception e) {
			e.printStackTrace();
		}
		return rrr;
	}

	public static byte[] hex2byte(byte[] b) {
		if ((b.length % 2) != 0)
			throw new IllegalArgumentException("长度不是偶数");

		byte[] b2 = new byte[b.length / 2];

		for (int n = 0; n < b.length; n += 2) {
			String item = new String(b, n, 2);
			b2[n / 2] = (byte) Integer.parseInt(item, 16);
		}
		return b2;
	}
    

    /** *//**
     * <p>
     * 公钥解密
     * </p>
     * 
     * @param encryptedData 已加密数据
     * @param publicKey 公钥(BASE64编码)
     * @return
     * @throws Exception
     */
/*    public static byte[] decryptByPublicKey(byte[] encryptedData, String publicKey)
            throws Exception {
        byte[] keyBytes = ConvertUtil.convertDecodeBase64(publicKey);
        X509EncodedKeySpec x509KeySpec = new X509EncodedKeySpec(keyBytes);
        KeyFactory keyFactory = KeyFactory.getInstance(KEY_ALGORITHM);
        Key publicK = keyFactory.generatePublic(x509KeySpec);
        Cipher cipher = Cipher.getInstance(keyFactory.getAlgorithm());
        cipher.init(Cipher.DECRYPT_MODE, publicK);
        int inputLen = encryptedData.length;
        ByteArrayOutputStream out = new ByteArrayOutputStream();
        int offSet = 0;
        byte[] cache;
        int i = 0;
        // 对数据分段解密
        while (inputLen - offSet > 0) {
            if (inputLen - offSet > MAX_DECRYPT_BLOCK) {
                cache = cipher.doFinal(encryptedData, offSet, MAX_DECRYPT_BLOCK);
            } else {
                cache = cipher.doFinal(encryptedData, offSet, inputLen - offSet);
            }
            out.write(cache, 0, cache.length);
            i++;
            offSet = i * MAX_DECRYPT_BLOCK;
        }
        byte[] decryptedData = out.toByteArray();
        out.close();
        return decryptedData;
    }*/

    /** *//**
     * <p>
     * 公钥加密
     * </p>
     * 
     * @param data 源数据
     * @param publicKey 公钥(BASE64编码)
     * @return
     * @throws Exception
     */
  /*  public static byte[] encryptByPublicKey(byte[] data, String publicKey)
            throws Exception {
        byte[] keyBytes = ConvertUtil.convertDecodeBase64(publicKey);
        X509EncodedKeySpec x509KeySpec = new X509EncodedKeySpec(keyBytes);
        KeyFactory keyFactory = KeyFactory.getInstance(KEY_ALGORITHM);
        Key publicK = keyFactory.generatePublic(x509KeySpec);
        // 对数据加密
        Cipher cipher = Cipher.getInstance(keyFactory.getAlgorithm());
        cipher.init(Cipher.ENCRYPT_MODE, publicK);
        int inputLen = data.length;
        ByteArrayOutputStream out = new ByteArrayOutputStream();
        int offSet = 0;
        byte[] cache;
        int i = 0;
        // 对数据分段加密
        while (inputLen - offSet > 0) {
            if (inputLen - offSet > MAX_ENCRYPT_BLOCK) {
                cache = cipher.doFinal(data, offSet, MAX_ENCRYPT_BLOCK);
            } else {
                cache = cipher.doFinal(data, offSet, inputLen - offSet);
            }
            out.write(cache, 0, cache.length);
            i++;
            offSet = i * MAX_ENCRYPT_BLOCK;
        }
        byte[] encryptedData = out.toByteArray();
        out.close();
        return encryptedData;
    }
*/
    /** *//**
     * <p>
     * 私钥加密
     * </p>
     * 
     * @param data 源数据
     * @param privateKey 私钥(BASE64编码)
     * @return
     * @throws Exception
     */
 /*   public static byte[] encryptByPrivateKey(byte[] data, String privateKey)
            throws Exception {
        byte[] keyBytes = ConvertUtil.convertDecodeBase64(privateKey);
        PKCS8EncodedKeySpec pkcs8KeySpec = new PKCS8EncodedKeySpec(keyBytes);
        KeyFactory keyFactory = KeyFactory.getInstance(KEY_ALGORITHM);
        Key privateK = keyFactory.generatePrivate(pkcs8KeySpec);
        Cipher cipher = Cipher.getInstance(keyFactory.getAlgorithm());
        cipher.init(Cipher.ENCRYPT_MODE, privateK);
        int inputLen = data.length;
        ByteArrayOutputStream out = new ByteArrayOutputStream();
        int offSet = 0;
        byte[] cache;
        int i = 0;
        // 对数据分段加密
        while (inputLen - offSet > 0) {
            if (inputLen - offSet > MAX_ENCRYPT_BLOCK) {
                cache = cipher.doFinal(data, offSet, MAX_ENCRYPT_BLOCK);
            } else {
                cache = cipher.doFinal(data, offSet, inputLen - offSet);
            }
            out.write(cache, 0, cache.length);
            i++;
            offSet = i * MAX_ENCRYPT_BLOCK;
        }
        byte[] encryptedData = out.toByteArray();
        out.close();
        return encryptedData;
    }
*/
    /** *//**
     * <p>
     * 获取私钥
     * </p>
     * 
     * @param keyMap 密钥对
     * @return
     * @throws Exception
     */
/*    public static String getPrivateKey(Map<String, Object> keyMap){
        Key key = (Key) keyMap.get(PRIVATE_KEY);
        return ConvertUtil.convertEncodeBase64(key.getEncoded());
    }*/

    /** *//**
     * <p>
     * 获取公钥
     * </p>
     * 
     * @param keyMap 密钥对
     * @return
     * @throws Exception
     */
  /*  public static String getPublicKey(Map<String, Object> keyMap){
        Key key = (Key) keyMap.get(PUBLIC_KEY);
        return ConvertUtil.convertEncodeBase64(key.getEncoded());
    }*/

	public static RSAPrivateKey getRSAPrivateKey(Map<String, Object> keyMap) {
		RSAPrivateKey rsaPrivateKey = (RSAPrivateKey) keyMap.get(PRIVATE_KEY);
		return rsaPrivateKey;
	}

	public static RSAPublicKey getRSAPublicKey(Map<String, Object> keyMap) {
		RSAPublicKey rsaPublicKey = (RSAPublicKey) keyMap.get(PUBLIC_KEY);
		return rsaPublicKey;
	}

	public static String getHexPublicExponent(Map<String, Object> keyMap) {
		RSAPublicKey rsaPublicKey = (RSAPublicKey) keyMap.get(PUBLIC_KEY);
		return new String(Hex.encodeHex(rsaPublicKey.getPublicExponent()
				.toByteArray()));
	}

	public static String getHexPrivateExponent(Map<String, Object> keyMap) {
		RSAPrivateKey rsaPrivateKey = (RSAPrivateKey) keyMap.get(PRIVATE_KEY);
		return new String(Hex.encodeHex(rsaPrivateKey.getPrivateExponent()
				.toByteArray()));
	}

	public static String getHexModulus(Map<String, Object> keyMap) {
		RSAPublicKey rsaPublicKey = (RSAPublicKey) keyMap.get(PUBLIC_KEY);
		return new String(
				Hex.encodeHex(rsaPublicKey.getModulus().toByteArray()));
	}
    
}
